In the electrolytic refinement of copper and certain other metals, metal layers are deposited on both sides of so-called mother plates which hang vertically from a horizontal rod, hereinafter called the yoke, having laterally and outwardly projecting parts which form electric contact means for the passage of electric current during the electrolysis process. The plates hang in mutually parallel and equidistant relationship in the tank. Subsequent to the refined metal having been precipitated to a desired thickness onto both sides of the mother plates, the mother plates with their metal layers deposited are moved batch-wise to a plant for further treatment. A primary operation in this plant is to strip the deposited layers from the mother plates. The plates are first advanced along a first horizontal path in the stripping and conditioning plant in their transverse direction. The plates are then transferred to a second path, in which they are conveyed in their longitudinal direction. The actual stripping operation is carried out in this second path. The mother plates are then transferred to a third path which extends parallel with the first path and along which the plates are again advanced in their transverse direction.
In the technique used at the present time, this technique having been practised for a very long time, the plates are normally moved along all three horizontal conveyor paths on chain conveyors or other types of endless conveyors. Conventional endless conveyors are also used in other mother plate treatment plants, e.g. plate washing or plate alignment plants, etc. SE 81013427, SE 329011, U.S. Pat. No. 4,577,401 and U.S. Pat. No. 4,069,925 disclose examples of this type of arrangement for conveying mother plates with or without deposited metal layers in conjunction with the pre-treatment or after-treatment of the mother plates in conjunction with the electrolytic refinement of metals.
A significant drawback with endless conveyors used in this technical field, normally chain conveyors, is that they are very expensive. This is mainly due to the harsh working environment of the conveyors. For instance, it is necessary to manufacture the chains and also support wheels and other devices from acid-proof steel, at least along parts of the conveyor line. The expensiveness of chain conveyors in this type of plant is also contingent on the necessity to manufacture bearings, bushes and the like from a special material. Another drawback with such conveyors is that they require the provision of separate devices for switching the plates from one conveyor path to another. In the absence of better conveyor arrangements, chain conveyors or other continuously working conveyors are still used in plants of the aforesaid kind in spite of these drawbacks.
It is also known to convey mother plates in their transverse direction with the aid walking beam conveyors. In this known technique, the plates hang from longitudinally extending rails on lugs which form electric contact devices on the plates in the electrolysis process. The plates are advanced with the aid of the walking beam conveyors with the platecarried contact lugs resting on said rails. One significant drawback with this method is that the lugs are subjected to a high degree of wear due to sliding on the carrier rails. Another drawback is that the rails do not indicate distinct plate positions as the plates are stepped forwards to new positions.